This invention relates to a photoelectric transfer device. More particularly, it is concerned with a photoelectric transfer device wherein a marked reduction in a generating efficiency is not observed in a photoelectric transfer element, a color tone in exterior appearance is particularly attractive depending upon its usage or its installed place and the color tone is not deteriorated and may be retained even after its use over a long period of time.
A photoelectric transfer device, inter alia, a solar battery has been recently installed in general houses or buildings as an electricity generation system utilizing sunlight and it has been also utilized for a desk-top calculator, a watch, etc.
However, the prior art solar battery has been designed to enhance absorption of light for increasing a generating efficiency and their exterior appearance has been limited to black-colored or similarly colored toward black so that it is restricted in its design. Accordingly, there has been raised the problem of the color tone when installed on the roofs of general houses or applied to the external walls of buildings.
There was also seen the case where installation of solar battery could not be admitted in a certain national park in view of the color tone problem. Moreover, there were some cases where it was difficult to be applied as exterior building parts or members.
In order to solve the above problems, there have been proposed several methods for coloring a photoelectric transfer device as seen, for example, in JP58-218179A, JP60-147718A, JP60-148172A, JP60-148173A, JP60-148174A, JP Hei 5-29641A, JP Hei 7-74380A, JP Hei 8-46228A, JP Hei 8-83920A, and Japanese Utility Model Kokai Applications Hei 5-93057 and Hei 4-97362.
Of these prior arts, JP58-218179A discloses a thin film solar battery wherein coloring agents such as dyestuffs and the like are incorporated into a light transmitting resin, but a generating efficiency is greatly reduced owing to optical absorption by the dyestuffs in this solar battery.
JP Hei 8-83920A discloses a solar cell wherein a thickness of a reflection protection film formed over the surface of a solar battery element may be controlled to adjust reflection factors to lights of various wave lengths, whereby different colorations may be developed. However, fabrication conditions for elements in this instance are required to be altered in compliance with the respective different colors, which leads to an expensive cost.
Other methods have been proposed to form a cholesteric polymer sheet and the like on the front face of a solar battery so as to selectively reflect the light of a specific wave length, whereby a colorful appearance may be available. However, the cholesteric polymer sheet tends to be deteriorated under irradiation of sunlight and the solar battery has not been fit to be used over a long period of time.
It is an object of this invention to solve the above problems and, more specifically, to provide a colorful photoelectric transfer device which can be fabricated at a low cost without any marked reduction in the generating efficiency of a photoelectric element and can be fit to be used over a long period of time.